Metering devices for dispensing a dose of pressurized fluid are generally known as metered dose valves by which pressurized fluids are dispensed from containers under pressure. Normally the liquid formulations administered by the metering valve include a liquefied gas propellant and are delivered to a patient in an aerosol spray. The dose of the administered formulation should be sufficient to produce the desired physiological response. The proper amount of the formulation must be dispensed to the patient in each successive dose. Thus, any dispensing system must be able to dispense doses of the liquid formulation accurately and reliably to assure the safety and efficacy of the treatment.
Such a metered dose valve is e.g. known from WO-A-2004/0022143 that includes a valve stem which is spring biased towards the valve opening. An interior chamber is defined by a spring cage having one or more inlets from an aerosol container. The upper end of the valve stem includes a metering gasket which is sealing a metering chamber if in the activated position. In the activated position transverse side holes in a longitudinal discharge passageway of the valve stem are discharging in the metering chamber, so that the metered dose of the formulation can be dispensed.
The volume of liquid dispensed by such metered dose valves is typically in the range of 70 to 140 microliters for each actuation. However, for certain applications, like applying a liquid spray to the back of the throat in order to prevent snoring, a larger quantity of the formulation is needed, e.g. around 1.5 ml for each actuation. Such large quantities cannot be dispensed by the known metered dose valves.
Further, the above mentioned metered dose valves are developed for aerosol containers. Since the environmental regulations require that the use of aerosols should be largely reduced, or even should be completely prevented, it is an object of the present invention to provide a metering device which can be used without an environmental problematic aerosol as propellant for the fluid formulation to be administered to a patient.
It is another object of the present invention to provide a metering device system which is capable of delivering a larger volume of liquid spray for each actuation, compared to currently available metered dose valves or manually operated pump spray systems.